Advanced filtration method makes it possible to extract water from biogas digestate and slurry, so that it can return to nature and remaining nutrients be recovered. Grundfos BioBooster’s Membrane Filtration Units play a decisive role.

Specially developed, patent protected technology with rotating ceramic membranes already have proved their worth, as they are key components in Grundfos BioBooster’s compact, decentralized solutions for wastewater treatment and water re-use. So far, they have primarily been utilized in the food and beverage industry and for treating municipal and hospital wastewater. Now they are a major factor in solving an agricultural problem.

The problem is that farmers must spend large amounts of money for storing slurry and digestate from biogas plants or for transporting and spreading it in the fields. This problem has now been solved by AMT Nereus, a Luxemburg/French based water company, situated in Luxemburg. Emmanuel Trouve, General Manager, AMT
Nereus, explains:

“A new,environment-friendly and economic method, developed and patent protected by us, means that farmers and biogas plants need much less storage capacity and much less transport. Our technology makes it possible to extract water from the digestate and slurry and clean it efficient enough to be discharged into streams in the local environment without any use of chemicals. At the same time, remaining nutrients will be separated for recovery.”

Need for robust membranes
The very heart of the extracting and treatment process technology is made up of a new original Grundfos BioBooster Membrane Filtration Unit, co-developed with AMT Nereus. Its task is to filter the slurry or digestate to a degree which only allows particles smaller than five nanometres to pass.

“This application demands robust membrane modules, being able to operate in very high concentrations of biomass. It fully benefits from our patent protected technology which makes it possible to detain a good deal of the nitrogen and phosphorus contents,” explains Jakob Søholm, Segment Director, Grundfos BioBooster. After having tested different membranes, available on the market, AMT Nereus signed a framework agreement with Grundfos BioBooster.

“Their Filtration Units turned out to be the best ceramic membranes for the application in terms of performance and economy. Add to this that we have good experience with Grundfos products and services,” explains Emmanuel Trouve.

The first order for in total 18 BioBooster Membrane Filtration Units for four biogas plant projects in Luxembourg and France is in the bag. According to Emmanuel Trouve, the market for the slurry or digestate solutions is huge, as there are 15,000 farms and 1,500 biogas plants in Europe.

“Our solution makes it possible to treat one cubic metre at a total price of five euro. This means that it is less expensive for the customers to use this than to store slurry or digestate or transport it over long distances and spread it in the fields,” he explains.